graw: fix logic error in pixel format selection

The loop to choose a pixel format for the window was incrementing
'i' after we succeeded in creating the window so if we chose format[0]
for graw_create_window_and_screen() we were putting format[1] in
the pipe_resource template for creating the render target.

This only worked because of the order of the elements in the formats[]
array.

The graw_xlib.c code now properly compares the requested gallium pixel
format against the visual's color layout.

Update all the graw demos to fix the off-by-one-i error.

1 files changed, 8 insertions, 5 deletions

diff --git a/src/gallium/tests/graw/tri.c b/src/gallium/tests/graw/tri.c
index 2742c7c99e..006d61ca88 100644
--- a/src/gallium/tests/graw/tri.c
+++ b/src/gallium/tests/graw/tri.c
@@ -162,13 +162,16 @@ static void init( void )
     * Also, no easy way of querying supported formats if the screen
     * cannot be created first.
     */
-   for (i = 0; 
-        window == NULL && formats[i] != PIPE_FORMAT_NONE;
-        i++) {
-      
-      screen = graw_create_window_and_screen(0,0,300,300,
+   for (i = 0; formats[i] != PIPE_FORMAT_NONE; i++) {
+      screen = graw_create_window_and_screen(0, 0, 300, 300,
                                              formats[i],
                                              &window);
+      if (window && screen)
+         break;
+   }
+   if (!screen || !window) {
+      fprintf(stderr, "Unable to create window\n");
+      exit(1);
    }
    
    ctx = screen->context_create(screen, NULL);